1. Field of the Invention
The present invention relates to an apparatus for independently controlling a volume of a speech signal extracted from an audio signal and method thereof, and more particularly, to an apparatus for independently controlling a volume of a speech signal by inverting a phase of a gain value corresponding to one channel of left and right channel whose phase is inverted and method thereof.
2. Discussion of the Related Art
Generally, an audio amplifying technology is used to amplify a low-frequency signal in a home entertainment system, a stereo system and other consumer electronic devices and implement various listening environments (e.g., concert hall, etc.). For instance, a separate dialog volume (SDV) means a technology for extracting a speech signal (e.g., dialog) from a stereo/multi-channel audio signal and then independently controlling a volume of the extracted speech signal in order to solve a problem of having difficulty in delivering speech in viewing a television or movie.
Generally, a method and apparatus for controlling a volume of a speech signal included in an audio/video signal enable a speech signal to be efficiently controlled according to a request made by a user in various devices for playing back an audio signal such as television receivers, digital multimedia broadcast (DMB) players, personal media players (PMP) and the like.
However, as phases of left and right channels signals are inverted due to such a cause as an error in transmission or intentionally, if a correlation between the left and right channel signals has a negative value despite a mono signal (e.g., if an input signal is spread widely rather than concentrated on a specific point on sound), the corresponding signal is not recognized as a speech signal due to the characteristics of SDV algorithm. Therefore, it is unable to control a corresponding volume.
Meanwhile, operation of the SDV algorithm needs to be manually controlled according to a request made by a user, it may be inconvenient for the user to use the television receiver or the like.